President Barack Obama and Congress are confronting a historic obstacle in their efforts to revive the stalled economy: a crippled housing market unlikely to rebound for several years.

And unless that market snaps back, any new extraordinary stimulus package to create jobs would fail, former Federal Reserve Chairman Alan Greenspan concluded.

“Until we can do that, it’s very hard for me to see how we get the unemployment down to an acceptable level,” Greenspan told a Washington audience last month.

Not every economist agrees with his assessment, yet there’s recognition that the traditional mechanisms of supply and demand have largely broken down. But the scope of the problem is unlikely to be eased by federal and state lawsuits designed to extract billions of dollars in damages from the banks involved in subprime lending.

In a speech last week that analyzed turning foreclosed homes into rental properties and other solutions, Fed governor Elizabeth Duke acknowledged the “market is not functioning as it should.”

“We, as a nation, currently have a housing market that is so severely out of balance that it is hampering our economic recovery,” she said. “Solutions aimed at righting the wrongs of previous reckless lending in the subprime market are not sufficient to tackle the scale of current problems.”

Lately, some administration officials have anonymously floated a plan to let mortgage holders refinance at lower rates, which would be in addition to an existing program that has helped more than 790,000 delinquent borrowers modify their home loans.

“It’s not the difference between a 4 percent and 6 percent interest that’s causing people to go into foreclosure,” said Stan Humphries, chief economist for real estate services firm Zillow. “Unfortunately, the market is going to have to heal itself on that front.”

Fed policy has pushed mortgage interest rates to an astoundingly low 4.22 percent. But a stream of buyers has yet to materialize — even as nationwide prices have collapsed to 2003 levels, according to the S&P/Case-Shiller Indices.

In short, several economists suggest plunging home prices have fed a vicious cycle: Stuck with less valuable homes, families have pulled back spending. And that, in turn, has stunted hiring, which prevents people from buying homes.

A typical consumer spent almost $100 a day three years ago, according to the pollster Gallup. Now, such spending hovers around $68.

U.S. Chamber of Commerce chief economist Martin Regalia said an increase in consumer spending depends on a housing recovery.

“We’ve lost a ton of net worth, and where we have to make that back is in the assets where we lost it,” he said. “There’s no other asset that’s going to step up and take over for the house, the home, in the average American portfolio.”

Unlike previous recoveries going back several decades, the financial crisis triggered in 2008 by the implosion of the housing bubble indicates the government cannot solely engineer a recovery through real estate, said David Crowe, chief economist at the National Association of Home Builders.

“Government can do some good,” he suggested, “but time and an improving economy will be the primary solution.”

While foreclosures have produced a glut of housing, Crowe explained that demand is also a major part of the problem. The downturn has prevented the formation of about 2 million new households over the past four years, he said.

People “stayed with roommates or their parents because they didn’t have the money to live independently,” Crowe said. “If that began to release, you would absorb the excess inventory and the pace of foreclosures wouldn’t be the focus that it is.”

Humphries expects the housing market to hit its trough sometime from 2014 to 2016, though he cautioned his estimate is based on “middling” job projections that now seem hopeful with unemployment stalled above 9 percent.

The housing recovery would not resemble a V-shape, where prices shoot back up, Humphries said. Instead, it would look like an L-shape with prices fluttering around the bottom for some time.

“It’s not getting back to the go-go years where you’re seeing appreciation of 5 [percent] to 10 percent a year,” he predicted.

The interconnection of housing, consumer spending and employment complicates attempts to revive the economy on an electoral timeline.

Regalia said the best government policy would involve allowing a painful but cathartic chain of foreclosures to proceed so the market can bottom out.

There are 10.9 million borrowers with homes worth less than their mortgages, according to Treasury Department records.

The current pace of foreclosure filings — about 212,000 in July — has only delayed an inevitable and painful reckoning, Regalia said.

“Negative equity situations are almost impossible to address without somebody taking a loss,” he explained. “The government has to take a loss to make good on these things, in which case we add to the deficit significantly. Or the individuals that hold those loans, namely the banking system, will take the loss.”

“Nobody is anxious to take a loss,” he added, “so everybody kind of drags their feet.”